Warehouse, office and retail mezzanine floors are built on the same steel principles, columns, beams and a deck, but the loading, fire protection, guarding and, occasionally, planning route change with what happens on top of the floor. A storage-only mezzanine with short escape routes can often stay as unprotected steel with a pallet gate for goods; an occupied office or retail floor almost always needs fire-rated construction and a protected staircase, and larger retail additions can need planning permission too. The table below sets out the differences at a glance; the sections after it give one clear recommendation per use.
| Warehouse / storage | Office | Retail | |
|---|---|---|---|
| Typical design load | Commonly 4.8 kN/m² general storage, 7.2 to 9.6 kN/m² heavy or palletised | Commonly 2.5 to 3.5 kN/m² | Similar to office unless heavier displays or stock require more, set by calculation |
| Fire protection | Often unprotected where escape routes are short and staff-only | Usually needed: fire-rated construction, protected stairs, alarm, emergency lighting | Usually needed; larger or multi-tier floors add extra measures |
| Guarding / access | Handrails, pallet gates, staircase for staff and goods | Staircase and handrails built for staff use | Handrails plus step-free access (lift) where the public visits |
| Planning | Normally none, internal alteration | Normally none, internal alteration | Normally none, except retail floorspace additions of 200 m²+ in England |
| Deck / finish | 38 mm chipboard, or mesh/durbar where ventilation matters | 38 mm chipboard with carpet or vinyl over it | Finished floor, suspended ceiling below, integrated lighting |
| Who it suits | Pallets, racking, stock, packing zones | Supervisor offices, meeting rooms, admin | Showrooms, sales floors, customer-facing display space |
(1 kN/m² is roughly 102 kg/m² of imposed load.)
For storage: design for the load, protect only where the rules require it
For storage, the loading rating is the whole design brief. General storage is commonly specified around 4.8 kN/m², heavy or palletised storage commonly 7.2 to 9.6 kN/m², and that figure sets the beam sizes and column spacing before anything else is decided. A storage-only mezzanine floor with short travel distances to an exit is often built as unprotected steel, since Approved Document B treats a short, staff-only escape route differently from an occupied floor. Guarding is handrails on the open edges plus a pallet gate for loading, under Approved Document K, and the staircase is sized for staff and goods rather than the public. Planning permission almost never applies. The deck is usually 38 mm P5 chipboard, or mesh or durbar where ventilation or washdown matters. Our mezzanine floor load capacity guide covers how the rating is set for your stock.
For an office: lighter load, heavier fire and access requirements
For an office deck, the loading rating drops to a commonly specified 2.5 to 3.5 kN/m², well below a storage floor, but almost everything else gets more demanding. Because the floor is occupied all day rather than visited to pick stock, Building Control typically expects fire-rated construction (a fire-rated ceiling, column casings or a fascia), a protected staircase, an extended fire alarm and emergency lighting (our mezzanine floor fire regulations guide covers the detail). Our internal steel staircases are designed to suit this, since a stair for occasional goods access is not the same as one built for daily staff use. Where the public visits too, Approved Document M starts to apply. The deck is the same 38 mm chipboard, finished with carpet or vinyl, with heating, data and lighting run in below a suspended ceiling. Read the mezzanine building regulations guide for what Building Control actually checks.
For retail: plan for the public, and check the 200 m² planning trigger
For retail, design for the fact that the public will use the floor. Loading tends to sit close to office levels unless heavier fixtures or stock genuinely need more, confirmed by the calculation rather than assumed. The bigger changes are access and planning. Approved Document M can require step-free access, a lift rather than stairs alone, where the mezzanine forms part of the public sales area. Fire protection follows the same logic as an office, usually needed, and larger or multi-tier retail floors typically add further measures. The genuinely retail-specific trigger is planning: adding 200 m² or more of retail floorspace in England can require planning permission under the Town and Country Planning Act 1990, even though most internal mezzanines do not. Our mezzanine floor planning permission guide explains when that applies. Finishes go further too, a finished floor, a suspended ceiling and lighting integrated into the design, because customers see this floor.
Mixed use: storage below, office above
The most common real-world mezzanine is not one use but two: a storage or warehouse floor at ground level with an office deck above it, or a single mezzanine split into a storage zone and an office zone. This is legitimate, but it has to be designed as one structure from the start. The steel is sized to the heavier load across each bay, storage load in the storage bays and office load in the office bays, not averaged across the whole floor. The fire strategy is built around the occupied part, a protected staircase and fire-rated construction for the office zone, even if the storage zone next to it stays unprotected, because Building Control looks at the whole means of escape together. Getting this split wrong after fabrication has started usually means reworking the frame, so it belongs in the structural engineer’s calculation and the industrial access steelwork design, not added on site.
What to decide before you ask for a quote
A few decisions, made before you contact a fabricator, make the quote faster and the design right first time:
- What will actually sit on the floor and roughly how much, since this drives the loading rating more than anything else.
- Who will use it: staff only, or staff and the public, since that decides the fire strategy and whether Approved Document M applies.
- Whether uses will be mixed (storage below, office above, or a split deck), so the frame is designed for both loads from the outset.
- The available clear height and floor area, so the design fits the building rather than being redrawn later.
We deliberately do not put a single price on these combinations; the mezzanine floor cost guide explains why area, loading, levels and compliance work all move the figure. A survey and a quote against your drawings is the only accurate way to price a specific floor.
How T C Rowan builds it
T C Rowan designs, fabricates and installs mezzanine floors from our own Banbury workshop, with one team from drawing to final bolt, working to BS EN 1090 execution standards. We build storage, office and retail floors, and mixed decks, across Oxfordshire, Buckinghamshire, Berkshire, Northamptonshire and Warwickshire, with larger projects taken on UK-wide. For the build sequence itself, see our how to build a mezzanine floor guide. We do not give a definitive fire or planning ruling on your behalf; that sits with Building Control and your local planning authority.
Get in touch for a free quote.
Frequently asked questions
What is the main difference between a storage mezzanine and an office mezzanine?
A storage mezzanine is usually staff-only, carries a higher loading rating for pallets or racking, and is often unprotected steel where escape routes are short. An office mezzanine is occupied space, so it carries a lighter loading rating but almost always needs fire-rated construction, a protected staircase and services such as heating and data. The two floors can look similar in steel terms but are designed to different rules because of who uses them and what they hold.
Does a retail mezzanine need planning permission?
Usually not, because an internal mezzanine is normally treated as an internal alteration rather than a change requiring planning permission. The exception is retail floorspace: adding 200 square metres or more of retail floorspace in England can trigger planning permission under the Town and Country Planning Act 1990, and a change of use can also trigger it. Confirm your specific project with your local planning authority before committing to a design. See our mezzanine floor planning permission guide for the detail.
Can one mezzanine combine storage below and office above, or does it have to be one use?
A single mezzanine can combine uses, most commonly storage or a warehouse floor below with an office deck above, or a mixed deck with a storage zone and an office zone side by side. The structure is then designed to the heavier of the two loads across the relevant bays, and the fire strategy and escape routes are designed for the occupied part, not the storage part. Mixing uses on one mezzanine is a design decision to make with a structural engineer before the steel is ordered, not after.
What loading rating do I need for a warehouse mezzanine floor?
There is no single figure, because the rating depends on what the floor will actually carry. General storage is commonly specified around 4.8 kN per square metre, while heavy or palletised storage commonly runs from 7.2 to 9.6 kN per square metre, against roughly 2.5 to 3.5 kN per square metre for office use. These are typical industry figures, not a rule for your project. The loading rating that applies to your floor comes from a structural engineer’s calculation for your intended use. See our mezzanine floor load capacity guide for more on how the rating is set.